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A long time ago I got a couple of solar panels, the largest being a 10W one. It was quite big, had strange connectors and all in all was more hassle than it was worth. Since then panels have got smaller, cheaper and, for our use, more convenient. The use of USB ports as an almost universal output has really boosted the practicality.

Firstly I know a lot of people are very anti technology and powered products when outdoors as they see it as a distraction from the peace and tranquility. I am largely with you on that, however, i am a big fan of taking pictures and now video as well sharing them here and on Facebook. All this requires power for the phone and cameras, with video being especially battery hungry. Up till now I have generally managed to get by with an external battery bank but I can see this needing topped up on longer trips, which is where my interest in solar panels has come in.

So lets start by talking about this particular solar panel then move onto more general points that will apply to most panels. The details and specification of the panel can be found here, http://www.gearbest.com/mobile-power...pp_144404.html along with the price (currently about £43.00 but if you use the discount code SOLARCHARGER you get about 10% off). The charger is a folding design with four actual solar panels with a total rated output of 14 Watts. Next to the SJ4000 it looks like this

and folded out

Now I'm no electrician, so I enrolled a friend who lectures in electronics and the like (Hi Tony) to do some testing for me and explain some details which I can hopefully convert into plain speak. I am paraphrasing and simplifying as I go along to give the big picture.

The power of solar panels is generally given in Watts. This is calculated by multiplying the voltage (Volts) by the current (Amps). Thankfully for us this is simple, as all USB sockets should output 5 Volts. Your bog standard USB phone charger usually puts out about 2.5 Watts, made up of 5 Volts at 0.5 amps (5V x 0.5A = 2.5W).

So the first thing we tested on this panel was the voltage. I’ll spare you the set up details and just tell you that in all but the very darkest conditions we got a consistent 5 Volts (actually about 5.2).

So we can pretty much forget about the voltage. There are two USB ports on the panel. One labelled 2.1 amps and one 2.5 amps. In practice there is no real difference in these; we never got as high as 2 amps. Jumping a bit ahead of myself I can tell you the highest we got was about 1.4 amps. That was in full sun, about 5pm in early May near Glasgow. All of that makes a difference. You would get less power in cloudy conditions, more at midday, more in the middle of summer, less in winter and more further south. The angle of the panel to the sun also makes a difference.

All of the above are why I wanted to try a 14 watt panel. In theory it should be over specified enough that you would still get a useable output in most normal conditions. This indeed proved to be true; in most conditions we were getting at least 0.5 amps and only rarely below 0.25 of an amp.

So what does all this mean in real life? Well as i have said 0.5 of an amp is about the same as a stock phone charger. So with this output your phone would charge just as fast as being plugged into the mains. The SJ4000 only draws about 0.25 amp so charges at full speed in even overcast conditions.

To get the best out of this or any solar panel you need to be aware of this limit on drawing of power. If you have the panel in optimal conditions where it is able to pump out 2 amps and you plug the SJ4000 into it then it only draws 0.25 of an amp and you are missing out on 1.75 amps. A phone will maybe draw 0.5 of an amp, with some we tried drawing 1 amp. An iPad Mini was our goto choice for seeing how high we could go. We suspect it would have taken 2 amps but we never got higher than 1.4 amps. Another factor is that some things will not charge unless they have a certain minimum current. iPhones, in my experience, are particularly choosy this way. Unless they are getting more than 0.5 amps they will not charge at all. So you could have a usable current that is not being drawn and therefore wasted.

The solution to all the above issues is to charge a battery bank. Ideally you want a decent capacity one that will trickle charge with low currents but still be able to charge up to 2 amps. Unfortunately for me, my external battery pack tops out at about 0.5 amps but does charge with even a tiny current of 0.2 amps and less. However this would be wasting a lot of the potential output from this folding solar panel so i am looking at a new battery bank. This set up allows you to connect the battery bank and leave it charging all day while you use your various cameras, phone etc. Then at night you can charge them while you are sitting round the camp fire, or sleeping. The solar charger itself is safe to use in the rain and it is simple enough to rig up some water protection for the battery bank. This way you can have the solar panel either draped over the canoe during the day while paddling between camps or set up at camp whatever the weather.

Another advantage of the battery bank option is it acts as a safety net between the solar panel and your expensive equipment. If something did go wrong with the solar panel and it fried the battery, it would less traumatic than your brand new smartphone giving out smoke signals.

So coming back to the review element of this long post. The panel itself is well made and the electronics do what you want. The voltage is regulated with the current being the part to fluctuate. From the tests we have done I believe the panel is capable of putting out 14 watts of power and in testing in Scottish weather and latitude you still get a useable amount of power out. Having had a 10 Watt panel years ago I was frankly stunned at how small and light this panel is. When it arrived I was sure it would not be anything like as powerful as advertised but I was proven wrong and am pleasantly surprised. All in all, I am very impressed with the solar panel. I just need to sort out the right battery bank to have my power needs sorted for my longer trips now.

a few years ago i was playing with a portable solar charger. it had only one panel, unwieldy pastic casing and was so temperamental that it was basically useless.
these here sounds an awful lot better, and like it would actually be useful.

now please stop talking to these gearbest people. too many new ideas to spend money and accumulate clutter...

It it seems a lot of us have tried solar panels before and found them wanting. It also seems like they may have now got to a stage where they can be useful.

Originally Posted by lowlander

now please stop talking to these gearbest people. too many new ideas to spend money and accumulate clutter...

You will be glad to know that I only have a mini review of a portable speaker left which is actually more of a competition to win one. Of course I am also writing up a review of the Thermarest 4 season mat with its new electric air pump and a the down blanket that can be used with it. I'm kind of using reviews at the moment as a driving force to make me get out more and do more outside trips

You'd need to be going away from power supplies for a number of days to make it worthwhile. Portable battery banks are now relatively high capacity and I tried one out on the weekend (11,000mAh)- that's the same as that solar kit above producing peak power for 8hrs (given you measured it at 1.4A max output). Given you'll generally get less than that- a battery bank of this capacity will produce as much power as the solar kit operating for 2 days. I used it to recharge a GoPro to 100% charge (from completely flat) and top up a Garmin Montana GPS (about 40% power prior to charging). That used less than half the power in the bank.

The advantage of using a battery bank is that I can leave it sealed up in dry bags during the day and be using my camera/GPS (inside their waterproof casings) and then recharge them when in camp overnight.

This looks like a very nice set up. I like the idea it is waterproof for canoeing. Issues that are of concern how easy is it to attach to the canoe to keep it facing the sun? Does it have a meter to indicate the current output? I have discovered a small angle change can dramatically change the power output. How does this help you keep it at the best angle? How well does it hold up? Flexing the wires dropping paddles on it and capsizing may reduce it's life. Can you let, Sam, play with it for an afternoon to see how it holds up? In general solar panels are an expensive way to purchase power because of the initial cost. Are these thin film panels or glass? What does it weigh?

I bought these 261319409348 from the bay, two 10w 6v panels for £18, (currently selling for £16 -so £8 each with free delivery). Solid with metal frames, they charge my phone as long as they are exposed to light, you don't need to point them at the sun but obviously the brighter the light the more power they make. I've soldered on a usb plug so any old usb cabled charge cable can be used for repsective devices. I don't think they have a diode in to prevent reverse charging but I'm not leaving anything on overnight anyway. I'll have a check later as a suitable diode would only be pence form maplin/bay anyway so would be an easy fix.

I have one. I haven't used it much, as I haven't had space for two stoves and didn't know if I could rely on finding suitable dry fuel. It works reasonably once you get it going, but it seems to need very dry wood. Maybe I just haven't learnt how to use it properly; I met a German kayaker who used it as his sole stove for a circumnavigation of Ireland.

<<www.aukey.com>> I bought a 21 watt 3 panel charger from Amazon for 50 dollars. I used it on two trips this summer and it does a great job of charging both my phone and camera. Cheap, reliable and easy to use.

I don't know what models they were, but both Dris and Sutchy used solar chargers in Rogen over the last few weeks, and definitely found them useful for topping up battery packs, and whilst we did have sun, usually it was grey skies.

Covering as many malmiles as possible before being distracted by the pub!

I don't know what models they were, but both Dris and Sutchy used solar chargers in Rogen over the last few weeks, and definitely found them useful for topping up battery packs, and whilst we did have sun, usually it was grey skies.

Anyone any ideas how to make a really waterproof, transparent case to let it charge in the boat please? Nothing commercial seems to be the right size (11.1 × 6.3in folded or 26.4× 11.1in opened) and Anker help line says they haven't anything to recommend......